A subscriber identity module (SIM) card is also referred to as a user identity identification card or a smart card, and only with this card mounted, a terminal such as a mobile terminal or a tablet computer can use a mobile communications data network (the mobile communications data network includes a second generation of wireless mobile telecommunications (2G), third generation of wireless mobile telecommunications (3G), or fourth generation of wireless mobile telecommunications (4G) network. For ease of description, a mobile communications data network is hereinafter referred to as a data network for short, and a network platform that provides a mobile communications data network service is hereinafter referred to as a data network platform). Currently, if a user wants to use a data network service of a mobile operator such as China Mobile, the user needs to apply for a physical SIM card at the operator's counter, and then mounts the physical SIM card on a terminal. An integrated chip on the physical SIM card stores authentication information, such as an identity of a terminal user and an encryption key, and a data network performs a network access authentication operation on the terminal user using the information.
Different terminals and different operators correspond to physical SIM cards of different specifications, and mobile service costs also differ significantly in different regions. A user who uses a roaming scenario much or roams many regions in a single trip needs to subscribe to a national or global data network roaming service in order to use mobile services in different regions. However, roaming costs are quite high. Costs can be reduced using a local data network service in a roaming region, but the user needs to buy a local physical SIM card, mounts the physical SIM card on the terminal, and sets a current SIM card of the terminal as a local SIM card. For a single-card terminal, only one physical SIM card can be mounted. Therefore, an original physical SIM card cannot be used any longer after a physical SIM card in a roaming region is mounted. In view of this, a multi SIM multi standby terminal is created. With multiple baseband chips disposed on such a terminal, multiple physical SIM cards can be mounted. However, when the user needs to frequently change a SIM card due to s service requirement, although multiple physical SIM cards can be mounted on the terminal, a buy and change process of the physical SIM cards is quite tedious. In addition, the user needs to select one from the multiple physical SIM cards to reserve and select one from the multiple physical SIM cards to change, and to determine which physical SIM card slot a physical SIM card is to be mounted in, the user needs to repeatedly detach physical SIM card slots for confirmation. This process is quite inconvenient.